Digestive System Unit 4 Flashcards
What is metabolism?
all chemical reactions within cells whether that be catabolic or anabolic
What do we take in to our digestive system?
Nutrients- carbohydrates, lipids, proteins, vitamins, minerals, and water
Why are we hungry? What stimulates hunger?
The hypothalamus regulates the feeding and satiety hormones. There are both neural and hormonal controls to stimulate hunger.
What is food broken into?
It is broken from complex to simple units in the digestive system.
Cells use _ to make ATP
small carbon chains (this yields 36 ATP/glucose)
Aerobic cellular respiration equation?
C6H12O6 + O2 -> CO2 + H2O + energy (ATP)
Aerobic cellular consists of 4 steps:
Glycolysis, preperatory reaction, citric acid cycle/krebs cycle, and oxidative phosphorylation
How will energy from nutrients be used?
muscle contraction, nerve impulse conduction, glandular secretions, cell growth, division, and repair and store energy
Innermost -> Outermost layers of the GI tract.
Mucosa, submucosa, muscularis, serosa
What is the function of the Digestive system?
transfers nutrients from external to internal environment
How does transport of nutrients happen (processes)
Ingestion, digestion, egestion, secretion, and absorption.
what is absorption?
simple molecules pass into blood or lymph vessels
small intestine..
large intestine..
-absorbs all nutrients
-absorbs water and vitamins
What are the types of digestion?
Chemical digestion and mechanical digestion
what is chemical digestion?
catabolic process, enzymes break complex molecules into simple molecules
what is mechanical digestion?
physical movements of digestive tract. (peristalsis and segmentation)
what is peristalsis?
unidirectional, forward propulsion
what is segmentation?
multidirectional mixing
What are the secretions of the digestive system?
Mucus, bile salts, HCL, pepsin, bicarbonate, enzymes
Mucus…
comes from GI tract, coats food, protects GI tract
Bile salts…
comes from liver and gallbladder, emulsify lipids
HCL and pepsin…
HCL (parietal cells), Pepsin (chief cells), both come from the stomach and aid in protein digestion
bicarbonate…
comes from pancreas, neutralizes acid
enzymes…
comes from salivary glands, stomach, pancreas, brush border. facilitates the break down of food, work best at specific pH
what does amylase break down?
starch/sugar
what does lipase break down?
fat
what does protease break down?
protein
Extrinsic neural controls…
occur along long reflexes, parasynthetic stimulation increases motility and secretion
Intrinsic neural controls…
Occurs along short reflexes, known as the enteric nervous system (gut brain)
intrinsic neural controls structure and function?
-nerve plexuses in muscle wall
-feedback loop regulates motility
oral cavity consists of what?
cheek muscles, tongue, uvula, teeth
what do the cheek muscles do?
aid in mastication (chewing)
what does the tongue do?
shapes food into bolus, contains taste buds
what does the uvula do?
seals nasal cavity so no food enters
what are the types of dentitions?
deciduous (baby) and permanent (adult)
how is mechanical digestion achieved in the oral cavity?
mastication
how does absorption occur in the oral cavity?
no nutrients are absorbed in the oral cavity, though some drugs are
how does chemical digestion occur in the oral cavity?
occurs with saliva which contains water, enzymes, electrolytes, and proteins.
functions of saliva?
begin starch digestion, cleanses mouth, moistens to articulate while speaking and ease swallowing.
what causes you to salivate?
salivary nuclei in medulla + pons, feedback with ANS
structure of the throat (pharynx)
muscular tube and sphincter at both ends
function of the pharynx
deglutition (swallowing)
1st phase of deglutition
1) Buccal: bolus moves from mouth to pharynx, tongue pushes bolus back, uvula raises to seal nasal cavity
2nd phase of deglutition
2) Pharyngeal: bolus moves from pharynx to esophagus, stretch receptors signal swallowing center (medulla) causing breathing halts. Larynx rises, epiglottis folds over glottis. Upper esophogeal sphincter relaxes.
3rd phase of deglutition
3) esophogeal: bolus moves from esophagus to stomach, peristalsis pushes bolus, gastroesophageal sphincter opens
stomach structure
rugae (folds of mucosa) when collapsed, gastric pits leads to gastric glands, 3 layers of muscle
stomach function
begins protein digestion. mix, churn, and pummel food. Absorption does not occur for nutrients yet
mucous cells
secrete mucus for stomach’s protective coating
enteroendocrine cells
secrete chemical messengers
chief cells
-secrete pepsinogen (activates pepsin, aids protein digestion)
-secrete gastric lipase, aids lipid digestion
parietal cells
secrete hydrochloric acid (HCl) (creates acidic conditions that activate pepsinogen)
how is HCl acid produced
comes from breakdown of carbonic acid. products are H+ and HCO3-. Antiporter shifts HCO3- into blood as Cl- enters into parietal cell
How does gastrin relate to regulating the stomach/intestines?
from the G cells (enteroendocrine) of stomach. Activated by presence of protein, high pH, or stretch of the stomach. Increases gastric secretions, stimulates protein digestions.
How does secretin relate to regulating the stomach/intestines?
from the enteroendocrine cells and duodenum. Activated by presence of chyme. Decreases gastric secretions/movements and increases bicarbonate ions which neutralizes acid.
How doe cholecystokinin (CKK) relate to regulating the stomach/intestines?
from the enteroendocrine cells and duodenum. Activated by presence of fatty chyme. Decreases gastric secretions, increases bile and pancreatic juice
phases of digestion in order
1) Cephalic
2) Gastric
3) Intestinal
Cephalic phase of digestion
initiated by taste/smell of food. neural stimulation causes gastric secretion
Gastric phase of digestion
food enters stomach, churning occurs. Gastrin stimulates gastric secretion and motility
Intestinal phase of digestion
about 4 hours after meal, small amounts of chyme released into duodenum. CCK + secretin inhibit gastric secretion and motility
small intestine regions in order
duodenum, jejunum, ileum
